This invention relates generally to a catheter device and methods for the site-specific delivery of agents to biological spaces in medical procedures. More particularly, the invention relates to a catheter device utilizing multiple balloons and a method of site-specific delivery of agents into blood vessels for treatment of the heart.
Heart disease (atherosclerotic cardiovascular disease) is the leading cause of death in the United States. One form of heart disease is caused by the formation of sclerotic plaques within blood vessels. These plaques prevent blood from flowing freely though vessels to the tissues the vessels supply. The most dangerous plaques are those which form in the coronary arteries, preventing the flow of oxygenated blood through the coronary arteries to the heart.
There are generally two surgical procedures for treating heart disease. One procedure involves methods to increase blood supply to the effected areas of the heart by clearing sclerotic plaques from the existing vessels. In angioplasty, for example, a small dilating balloon is inserted into the vessel to open the vessel to increase blood flow. A second procedure involves providing new pathways for blood flow. New pathways can be created by grafting in vessels (coronary artery bypass surgery) or inducing the growth and development of new collateral vessels (therapeutic angiogenesis).
The induction of new collateral vessels can be achieved by injections of angiogenic agents directly into the heart tissue, vessels (coronary arteries), or the space surrounding the heart (pericardium). Direct injections of agents into the heart muscle or vessels can result in tissue injury, scarring and rapid washout of the agent away from the target site. Furthermore, these direct injections require a surgical procedures which are more costly and require a longer recovery period than catheter based procedures.
Catheters have been designed using occlusion balloons to create a pocket for drug delivery within a vessel. See, for example, U.S. Pat. No. 4,824,436 to Wolinsky, which has been incorporated by reference as if set forth herein. The balloons of the Wolinksy catheter prevent agents from escaping distally or proximally from the target zone of the vessel. One problem that this design does not address, however, is the washout of the delivered therapeutic agent through side branch vessels which may be within the target vessel segment.
Particularly with injections into the coronary artery, side branches coming off of the coronary artery can siphon agents away very quickly, thus reducing the concentration of the agent and the duration during which the agent is in contact with the target tissue. The reduced concentration and the reduced time of exposure make it less likely that the agent will have the desired effect on the target tissue. One way to address the washout through side branches is to use a catheter which occludes the side branches.
Introducing an agent to the target vessel while the side branches are occluded allows the agent to be contained in a precise segment of the target vessel. This is beneficial in that: 1) a lower dose of drug can be used due to the low blood volume of the occluded vessel segment, 2) the low rate of escape via side branches allows a higher concentration of the agent to be maintained at the target site over a longer period, and 3) the agents are kept out of systemic circulation where the agent may cause adverse side effects.
However, the side branch vessels are small and thus difficult to access. A further concern is that in placing an occlusion balloon directly into a branch vessel it creates the risk that the vessel could be punctured (and damaged), which could lead to bleeding. Thus, a catheter device and method of delivering agents site-specifically to the target vessel which minimizes these risks is needed.